Teaching and Teaching Duties of Ph.D. Students
This our group treats all “wissenschaftliche Mitarbeiter” (that is, internal Ph.D. students) the same. The University-imposed teaching duties of 5 SWS for a Landesstelle are spread over all internal Ph.D. students (the larger we grow, the smaller the individual requirements become). Teaching duties, but more importantly career development, beg the question what and how much to teach. It is up to the professor to define the teaching his or her Ph.D. students perform, so here is how I think about it.
As to teaching courses, internal Ph.D. students should support the professor. This involves helping with homework exercises and evaluation, or helping in class. A few times, it means actually holding the class. The general idea here is that during a group member’s career as a Ph.D. student they should experience what it means to teach without having the burden of full responsibility. Based on this experience they can then decide whether to pursue an academic career (which will inevitably involve teaching) or not. At this stage of their career, developing and running their own classes is counterproductive. It is not a necessary experience and it distracts from what internal Ph.D. students should be focused on: Moving their research project forward and writing their dissertation.
As to supervising student theses, internal Ph.D. students should only take on Bachelor and Master students whose work is aligned with their dissertation. No professor and no Ph.D. student who the professor delegates to is required to take on a student who comes asking for a final thesis. (If a student cannot find a supervisor for their thesis, the department will allocate them to a professor, who will then define the topic for the student.) Thus, in any case, the final thesis of a student can and should be aligned with the Ph.D. students research objectives.